Can I temporarily replace an object with a "placeholder" to help with multiple high-detail objects?
Select your high poly object
Go to Object Properties panel
Under display tabs, look for "Maximum Draw type"
Choose "Bounds" in the selection drop down.


Now your high poly mesh will be displayed as a simple box in the viewport.



Alternative Method

Or you could add a decimate modifier on the high poly object which would let you pull down the mesh count considerably. When you have finished positioning all the mesh all you need to do is to remove the modifier so the high poly object is restored.